1. Field
This disclosure relates to materials and compositions for servicing a wellbore. More specifically, this disclosure relates to introducing materials and compositions into a wellbore penetrating a subterranean formation to reduce the loss of fluid to the formation.
2. Background
A natural resource such as oil or gas residing in a subterranean formation can be recovered by drilling a well into the formation. The subterranean formation is usually isolated from other formations using a technique known as well cementing. In particular, a wellbore is typically drilled down to the subterranean formation while circulating a drilling fluid through the wellbore. After the drilling is terminated, a string of pipe, e.g., casing, is run in the wellbore. Primary cementing is then usually performed whereby a cement slurry is pumped down through the string of pipe and into the annulus between the string of pipe and the walls of the wellbore to allow the cement slurry to set into an impermeable cement column and thereby seal the annulus. Subsequently, oil or gas residing in the subterranean formation may be recovered by driving the fluid into the well using, for example, a pressure gradient that exists between the formation and the wellbore, the force of gravity, displacement of the fluid using a pump or the force of another fluid injected into the well or an adjacent well.
Fluids used in servicing a wellbore may be lost to the subterranean formation while circulating the fluids in the wellbore or otherwise placing the fluids in the wellbore. In particular, the fluids may enter and be “lost” to the subterranean formation via depleted zones, zones of relatively low pressure, lost circulation zones having naturally occurring fractures, weak zones having fracture gradients exceeded by the hydrostatic pressure of the drilling fluid, and so forth. As a result, the service provided by such fluids is more difficult to achieve. For example, a drilling fluid may be lost to the formation, resulting in the circulation of the fluid in the wellbore being terminated and/or being too low to allow for further drilling of the wellbore.
When considering remedies for lost circulation, a factor is the relative polarity of the subterranean formation which may be hydrophobic or hydrophilic depending on exposure of the surfaces of the subterranean formation to one or more oil-based or aqueous-based substances. As such, there is a need to consider the compatibility between the materials used to combat lost circulation and the surface of the subterranean formations with which they will interact (e.g., a surface associated with a lost circulation zone).
Accordingly, an ongoing need exists for compositions and methods of blocking the flow of fluid through lost circulation zones in subterranean formations.